Plant Green Giant arborvitae any time between early spring and late fall. Select an appropriate planting site. Green Giant arborvitae should be planted in full sunlight, although they can do well in partial shade if you live in an area with very hot summers.The tree will do well in most types of soil, as long as it has good drainage.
Give Green Giant arborvitae plenty of growing space. Don't plant them under power lines or too close to a building, sidewalk, street or street sign.
Dig a hole the height of the arborvitae's root ball, and three times as wide. Reserve the soil. If you are planting more than one Green Giant arborvitae, leave 15 feet between each tree.
Remove the Green Giant arborvitae from its container. If the roots are tightly matted, tease them apart carefully with your fingers before planting the arborvitae. If the tree is wrapped in burlap, remove any strings or wires, then either remove the burlap, or fold it down so that the top third of the root system is uncovered. If the roots are wrapped in synthetic burlap, it must be removed.
Spread the roots out evenly, and plant the Green Giant arborvitae in the hole. The crown of the tree, which is where the trunk meets the root system, should be about 2 inches above the soil, so adjust the soil in the bottom of the hole to bring it to that level, if necessary.
Let a garden hose run slowly on the base of the tree. Once the water settles, it may be necessary to add more of the reserved soil.
Stake Green Giant arborvitae after planting, and keep them staked until the roots are well-established, especially if they're planted in a windy area. Drive three stakes into the soil around the tree, and tie it to the stakes with strips of fabric, soft rope or nylon stockings. Tie the tree loosely so it can move in the wind and develop a strong trunk.
Water Green Giant arborvitae heavily for the first year while the roots are getting established. Water slowly with a garden hose, or use a soaker hose. After the first year, the trees will need on an occasional watering, especially during hot, dry weather.
Feed Green Giant arborvitae a balanced fertilizer in late winter and again in midsummer. Use a fertilizer formulated specifically for trees and shrubs, and apply it according to the directions on the package.
Remove any dead branches that typically accumulate near the bottom of the Green Giant arborvitae. Green Giant arborvitae need no pruning, unless you want to even out the tops or edges. Prune lightly, and never prune past green growth and into bare wood, because the greenery won't grow back.